Circuit-breaking apparatus



N. J. CONRAD.

CIRCUIT BREAKING APPARATUS.

APPLICATION FILED MAR. 3. 1919.

1,335,045, Patented Mar. 30, 1920.

2 SHEETSSHEET 1.

N. J. CONRAD.

CIRCUIT BREAKING APPARATUS.

APPLICATION FILED MAR. 3, 1919.

1 ,335,04:5. Patented Mar. 30, 1920.

2 SHEETS-SHEET 2.

QZZozzneys NICHOLAS J. CONRAD, OF CHICAGO, "ILLINOIS.- I

CIRCUIT-BREAKING APPARATUS.

Specification of Letters Patent.

Application filed March 3, 1919. Serial No. 280,398.

To all whom it may concern:

Be it known that I, NICHOLAS J. CONRAD, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in' Circuit-Breaking Apparatus, of which the following is a full, clear, concise, and exact description, reference being had" to the accompanying drawings, forming a part of this specification.

My invention relates to a circuit breaking apparatus, and more particularly to a means for interrupting current flow at moderate and high tensions.

In his pending application, Serial Number 270,483, filed January 10th, 1919, Edmund O. Schweitzer has disclosed a method of interrupting a flow of current which comprises placing a fuse in shunt of a disconnecting switch which is incapable of satisfao torily interrupting the flow of current at the voltage at which the line is operated, and placing the actual duty of interrupting the current flow upon the fuse, the fuse being of such character and construction as to be capable of interrupting the flow of current at any voltage to which the line is subjected. The fusible circuit-breaking device employed in the above application, and which I preferably employ ,in the present application, is ofthe type shown in the patent to Mr. Schweitzer and myself, 5,548, granted April 13, 1915,

Number 1,13 although any fuse of similar characteristics and ability to positively interrupt the circuit may be employed instead. .This type of fuse is particularly valuable because of being surrounded by liquid. It is capable of carrying a large overload current for a very short period of time without fusing, thus permitting the switch to be opened far enough to prevent reformation of the arc at the contact of the switch, and also because of the ability to positively interrupt the flow of current at the fuse.

I have found that disconnecting switches carrying current are frequently opened by magnetic forces when short circuits occur or that operatlng englneers frequently feel ing sure that a disconnectmg switch is not carrying current, fail to place a fuse in shunt with the switch before opening the same, or feeling sure that the right switch is being opened-a switch that is not carrying current-a switch carrying current is opened by mistake without placing a fuse in shunt with the switch, or otherwise providing for making the operation of the switch safe.

The hazard attending the accidental opening of disconnecting switches that are carrying current, as when short circuits occur, and the intentional opening of disconnect: ing switches that are carrying current, but which are not supposed to be carrying current, is only too well known to those skilled in the art. The disastrous results have taken a. heavy toll in lives, besides the enormous damage done to apparatus, and to the morale of the operators wherever these accidents have occurred. These accidents are by no means necessarily the result of carelessness on thepart of the operator, as there have been numerous instances where oil switches have failed to operate properly and the operator, believing the oil switch was open, opened the disconnecting switch without first providing adequate means for the safe operation of the switch ;the contact of the oil switch being inclosed in the oil pots,

contacts had failed to separate, and that the disconnecting switch was therefore still carrying a current. After the disconnecting blade has been opened, and the resulting arc has flared into the surrounding structural iron, causing great damage and perhaps loss of life, it is too late to rectify the error.

The present invention provides a safety locking device which positively prevents opening of the blade disconnect until adequate means for making the operation thereof safe has been provided. Thus I have provided positive insurance against the inevitable damage and perhaps loss of life which has heretofore resulted whenever a blade disconnect has been opened while carrying current, without adequate means for making the operation thereof safe.

In accordance with the teachings of my Patented Mar. 30, 1920.

there was no way of knowing that the invention T have provided a safety locking device for the blade disconnect, which safety locking device is arranged so that to release the same necessitates inserting a suitable fuse in shunt with the switch. The safety locking device, and consequently the blade disconnect is adapted to be released automatically upon the insertion of a suitable fuse, whereupon the disconnect blade may be safely opened. In case the disconnect is carrying current when it is opened, the

flow of current will be interrupted by the blowing of the fuse, the are being quickly and effectively extinguished within the fuse by a dielectric medium of great strength. If the disconnect is not carrying a current when it is opened, the fuse will be unaffected, and no expense will be involved, although the safety of such an operation has been positively insured.

Heretofore, in the art, complicated locking mechanisms have been employed for locking the movable switch member against opening, due to magnetic forces When short circuits occur, and against such opening as might result from vibration of the switch supports or insecure contact between the movable switch member and the switch terminals. Generally, such locking mechanisms are expensive and complicated, and necessitate a deliberate predetermined act on the part of the attendant in order to open or close them.

My improved safety locking device, which is of simple and inexpensive construction, and is positive in operation, in addition to preventing opening of the blade disconnect until adequate means has been provided for making the operation thereof safe, normally prevents opening of the movable switch member, due to magnetic forces when short circuits occur, and such other accidental openings apt to occur, as has been explained. Thus, the ordinary complicated locking mechanisms heretofore employed are dispensed with. I

In order to acquaint those skilled in the art with the manner of constructing and practicing my invention, I shall now describe in detail a specific embodiment of the invention, and the novel manner of opera tion of the same in connection with the accompanying drawings which form a part of the present specification.

Figure 1 is a front elevational View of a typical disconnecting switch showing the safety locking device of my invention applied thereto;

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. 1 showing the position automatically assumed by the locking device upon the provision of adequate means for making the operation of the switch safe;

Fig. 3 is a View similar to Fig. 2, showing the normal position of the locking device, the disconnect blade being positively locked against opening until adequate means for making the operation thereof safe has been provided; and,

Fig. 4 shows in isometric a modified form of mounting for the locking device.

In the drawings, I have shown a switch 1 which may be of any suitable or desirable type, preferably of the blade disconnect type. This switch is connected into the line in normally closed position.

The disconnecting switch 1 comprises a blade member 2, having an eye 3 at the upper free end thereof; the opposite end of the blade member 2 being pivoted in suitable hinge aws 4. A hinge pin or bolt 5 is passed through the hinge jaws 4, and through the lower end of the blade member 2, thereby forming a pivot for the movable blade member 2. The movable blade member 2 is thusgripped between a pair of hinge jaws 1 and held in place yieldingly by means of suitable spring washers 6, and the bolt 5. The eye 3 is provided in the uper free end of the blade member 2, in order that the blade 'may be manually opened-or closed.

The hinge jaws 4 extend from the base portion 7 of the lower contact member, which base portion 7 is mounted upon a cross-bar or connector 8. The base portion 7 of this lower contact member is provided with a terminal lug 9 extending longitudinally d0wn\\'ardl therefrom, as isshown in Fig. 1. A socket terminal 10 is mounted upon this terminal lug 9, by means of a suitable bolt 11.

The spring jaws 12 which extend from the base portion 13 of the upper contact member engage the upper free end of the blade member 2, thereby completing the en'- cuit between the socket terminals 10 and 14, in which socket terminals the line wires are suitably secured. The socket terminal 14 is mounted upon a terminal lug 15, which terminal lug extends longitudinally upwardly from the base portion 13 of the upper contact member. The base portion 13 and consequently the entire upper contact member is mounted upon a cross-bar or connector 16.

The cross-bar or connector 16 is mounted upon a post insulator 17, the cross-bar or connector 8 of the lower contact member being mounted upon a post insulator 18. The post or supporting insulators 17 and 18 are securedor fixed upon a suitalile base plate 19, whereby the entire unit may be bolted upon a suitable wall, cross-arm or the like.

The cross-bars or connectors 8 and 16 extend substantially horizontally from the insulators 17 and 18 respectively, as shown in Fig. 1. Spring contact clips 20 and 21, are

mounted upon the outer free ends of the cross-bars or connectors 8 and 16 respectively. The spring contact clips 20 and 21 are adapted to embrace the metallic ferrules or terminals 22 and 23 of the fuse 24. The spring contact clip 20 is provided with a stop support 25 for insuring the correct p0- sition of the fuse 24 in the spring contact clips 20 and 21, and for supporting the lower end of the same to prevent actual displacement of the fuse.

The fuse 24 which I have shown is of the type disclosed in the patent to Mr. Schweitzer and myself, Xumber 1,135,548, granted April 13, 1915, although any fuse of similar characteristics and ability to positively interrupt the circuit may be employed instead. This fuse is of the inclosed type, and is provided with an arc extinguishing liquid of high dielectic strength such as carbon tetrachlorid. The fuse comprises a sleeve of glass or other insulating material having brass ferrules 22 and 23 at the top and bottom, which ferrules are cemented in place on the sleeve. A fusible element inclosed in a cork barrier 26 is connected to a removable vent or disk 27 by a suitable link not shown. The vent or disk 27 is soldered on the upper ferrule and adapted to be blown off in the case of vigorous blowing of the fuse. The lower end of the fusible element is connected through a suitable link, and cross-bar (not shown), to a wooden liquid director 28. The liquid director 28 is connected to a helical spring 29, the lower end of which is connected to the lower ferrule 22. A flexible cable 30 is connected in shunt of the spring 29 to prevent overheating and destruction of the temper of the spring. The entire sleeve is filled with carbon tetrachlorid or other similar suitable insulating material. lVhen the fusible element is fused the spring 29 draws one of the fuse terminals down into the sleeve and at the same time liquid is projected in a stream by the liquid director 28, thus positively interrupting the flow of current. The fusible element. is

i made of a small per cent. of the carrying capacity of the main switch, to which it is adapted to be connected in shunt through the cross bars or connectors Sand '16. The: resistance is also preferably made sufficiently high so that when the element is connected in shunt of the switch, the flow of current through it will be small enough not to blow the fuse under all conditions of current flow to which it is subjected when the switch blade 2 is closed.

The safety locking device of my invention, which safety locking device positively prevents movement of the blade member 2 away from the spring jaws 12 until adequate means for making such operation safe has been provided, comprises a bell-crank lever 35,

pivotally mounted upon a bolt 36, the shank of which bolt 36 extends through the bellcrank lever, and is threaded into the lower edge of the base portion 13 of the upper contact member. The forwardly extending arm of the bell-crank lever 35 is provided with a hook or catch 37 adjacent its outer free end. A spring 38 is connected to this forwardly extending arm of the'bell-crank lever 35, the opposite end of which spring 38 is connected to a suitable pin or set screw, projecting from the base portion 13 of the upper contact member. Thus, as shown in Fig. 3 movement of the blade member 2 away from the spring jaws 12 is normally prevented by reason of the normal engagement of the hook or catch .37 with a lug or detent 40, which lug or detent is mounted as by means of a suitable set screw upon the side of the blade member 2 adjacent the inner edge thereof.

The transversely extending arm- 41 of the bell-crank lever 35 is provided with an upwardly extending portion 42. This upwardly extending portion 42 is arranged substantially longitudinally in the spring contact clip 21 normally in the position shown in Fig. 3, so that upon inserting a fuse in the spring contact clips 20 and 21, this upwardly extending portion 42 will be in the path of movement of the fuse, being thereby engaged and moved into the position shown in Fig. 2. It will now be apparent that until the insertion of a suitable fuse in the spring contact clips 20 and 21, the bellcrank lever 35 will remain in the position shown in Fig. 3, the hook or catch 37 thereof positively retaining the blade disconnect 2 against accidental or intentional opening. To open the blade disconnect 2 necessitates the insertion of a suitable fuse 24 in the spring contact clips, 20 and 21, whereupon the safety of such an operation will be positively insured, if the switch is carrying current when opened, by conducting the energy normally carried by the blade member 2 through the fuse. The fuse will thereupon be blown, the are formed within the fuse being extinguished almost instantaneously, as has been described. As hereinbefore stated, the particular form of fuse shown is preferable.

In Fig. 4 I have shown a modified form of mounting for the bell-crank locking lever In this case a standard type of contact member 45 comprising a base portion having spring jaws 46 extending therefrom, is mounted upon a crossbar or connector 47 between a pair of transverse bosses 48 and 49 which transverse bosses are formed integral with the upper surface of the crossbar 47. The boss 48 is drilled and tapped for the reception of a suitable bolt whereby the bell-crank lever 35 is .pivotally mounted upon the cross-bar. The boss 49 is drilled and preferably tapped for the reception of a suitable pin or set screw, whereby one end of the spring 38 is fixed to the cross-bar 4:7, the other end of the spring being connected to the forwardly extending arm of the bell-crank lever, as explained in connection with Figs. 1, 2 and 3.

Instead of fastening a block or detent 40 upon the side of the switch blade I may provide a longer detent as shown in Fig. 4, to engage the top surface of the blade or I may cut a recess or a hole in the switch blade so that the catch may engage in the same. The particular form in which these parts may be made is not of the essence of the invention.

From the foregoing, it will be apparent that I have provided a simple, inexpensixe and reliable mechanism for positively preventing opening-of the disconnecting switch until adequate means for making the operation thereof safe has been provided.

I do not intend to be limited in the operation of this feature of my invention to any particular type of switch, as it is apparent I that the advantages of my invention can be secured regardless of the particular form of switch employed. It is apparent that although the particular type of fuse shown and described is preferable, any fuse of similar characteristics and ability to positively interrupt the circuit may be employed instead.

I wish it to be understood that while I have described my invention in connection with the details of a particular embodiment, I do not intend thereby to limit the invention to such details, as am. aware and contemplate that modifications and changes may be made without departing from the invention, which is set out in the appended claims.

I claim:

1. In combination, a pair of insulators, metallic connecting pieces mounted upon said insulators, a pair of line terminals connected to said metallic connecting pieces, a disconnecting switch normally connected across said connecting pieces to close the line circuit, spring jaws mounted on each of said connecting pieces,.said spring jaws being adapted to receive a fusible circuit breaking device. detent means carried by the disconnecting switch. and a trigger cooperating with said detent means for normally holding'the switch in a closed position, releasing movement of said trigger being effected by placing a fusible circuit breaking device in said spring jawsin contact with said trigger.

2. In combination, a pair of connecting pieces, a pair of terminals, :1 switch blade mounted in one of said terminals, a contact on the other terminal for engaging the switch blade, fuse clips electrically connected to said connecting pieces, and locking means for said switch blade, releasing movement of said locking means being efi'ected .by the insertion of a fuse in said fuse clips.

until a suitable circuit breaking device has been connected in parallel with the switch, whereupon said locking means will be actuated to release the switch.

5. In combination, a switch, locking means for holding the switch in closed position until a suitable circuit breaking device has been connected in parallel with the switch, whereupon said locking means will be actuated to release the switch, said fusible circuit breaking devicehaving means to delay the blowing of the same until after the switch is opened a substantial distance.

6. In an electrical switch, switch terminals, a switch member adapted to connect said terminals, and locking means for locking said-switch member in closed position, said locking means being automatically released upon the provision of adequate means for making the opening of the switch safe.

7. In combination, a pair of metallic connecting pieces adapted to be placed in an electrical connection, a pair of terminals mounted upon said connecting pieces, a

switch blade pivoted in one of said terminals, the other of said terminals having contacts for engaging the switch blade, a bellcrank lever 'pivotally mounted upon one of said terminals, terminal clips electrically connected with each of said metallic conand arranged in the path of movement of a fuse, so that upon inserting a fuse in said terminal clips, said bell-crank lever will be actuated to release the switch blade.

8. In combination, a switch having a blade, a pivot terminal and a contact terminal locking means for preventing the opening of the switch blade, a fuse and fuse clips adjacent the terminals of the switch for connecting the fuse in parallel with the switch, said fuse when inserted into or withdrawn from the fuse clips controlling said locking means.

9. In an electric circuit, a switch comprising a pair of terminals and a blade, detent means for locking the blade in a predetermined position, stationary fuse contact telminals and a removable fuse for said latter terminals, sald detent means havlng releasing means extending into position to be engaged by the fuse When it is inserted in said latter terminals.

10. In combination, a switch, a fuse adapted to be connected in parallel With said switch, and locking means normally locklng the switch, said means being released when the fuse is connected.

In Witness whereof I hereunto subscribe my name this 27th day of February, A. D. 

